Apparatus for excavating deep holes and trenches

ABSTRACT

An apparatus for excavating holes and trenches, including a multi-jaw grab bucket with a driving rod having a screw-threaded section. The jaws are articulated at one point through connecting arms to a nut screwed on said screw-threaded section and at another point to an articulation member idle on the extremity of said driving rod. The nut screw has a sleeve extending at least over a portion of the driving rod beyond said screw-threaded section and defining therebetween an interspace for a lubricant. A counter sleeve member telescopically engages the sleeve and surrounds at least said screw-threaded section of said driving rod and defining therebetween a further interspace for lubricant. The counter sleeve member is connected with said articulation member. One of the interspaces is connected to an external reservoir with at least one expandable wall.

11. 3,750,770 Aug. 7, 1973 United States Patent 1 1 Botto 1 APPARATUS FOR EXCAVATING DEEP HOLES AND TRENCHES Primary ExaminerDavid H. Brown Atmrney- Guido Modiano and Albert Josif Giuseppe Botto, Via Della Rovere 7,

[76] Inventor:

1 .W 39 I w s ad gV 0 SN m k H -jaw grab bucket with a driving rod hav- Appl. No.: 198,665

ing a screw-threaded section. The jaws are articulated at one point through connecting arms to a nut screwed Related US. Application Data Continuation-in-part of Ser. No. 791,701, Jan. 16,

on said screw-threaded section and at another point to y of said 1969, Pat, No. 3,640,353.

an articulation member idle on the extremit driving rod. The nut screw has a sleeve ext ending at least over a portion of the driving rod beyond said screw-threaded section and defining therebetween an interspace for a lubricant. A counter sleeve member telescopically engages the sleeve and surrounds at least said screw-threaded section of said driving rod and defining therebetween a further inters n m 3 7 N H 54 5 2 7 9 H m 2 m was a H 2 9% D H V 7m W 177 HU .m u bm r m P u m n N 0 "u mu m .wm m u m u P m h A7 m N W mu w l r l .f 0% Cfl w S .M M mk UIF .ll. 1]] 0 2 8 3 555 m. a m H& bs U mm 3 e Cm ac Die [56] References Cited The counter sleeve member is conn UNITED STATES PATENTS ticulation member. One of the interspaces is connected to an external reservoir with at least one ex wall.

pandable 175/238 8 Claims, 7 Drawing Figures 175/238 X 246 6/1940 Zum-Berge 458 7/1953 Yost...............

629 12/1963 Allard 329 7/1965 Wallers.....................

PAIENIEU W8 3.750.170

SHEEI 1 0F 3 HNVENTOR Giuseppe BOTTO BY AGENT PAIENIEBAUQ 71m SHEET 3 OF 3 Fig. 5

APPARATUS FOR EXCAVATING DEEP HOLES AND TRENCHES.

CROSS REFERENCE To RELATED APPLICATIONS This is a continuation-in-part of my copending application Ser. No. 791,701, filed on Jan. 16, 1969, now US. Pat. No. 3,640,353.

BACKGROUND OF THE INVENTION The parent patent describes and claims an apparatus for excavating holes and trenches of the type formed from a multi-jaw grab bucket in which the jaws are joined articulated at one point by way of arms to a nut screw capable of axial movement on a screw, and at another point to a member mounted idly n the terminal section of said screw.

More particularly the object of the inventionaccording to the parent patent and according to the present continuation-in-part is'an excavation apparatus which comprises in combination the characteristic of being constituted of an implement which may be coupled to the equipment of a normal rotary drill (as a replacement for the normal bit equipment or the like), and hence able to take advantage of the considerable power and considerable weight of the rotary drill rod, and in which the implement includes a screw and nut screw mechanism, i.e. capable of exploiting to a maximum mechanical level the high power constitutionally available in said rotary drills or rotary table drillers.

It is conventional to transmit a closing action to the jaws or blades of a grab by using hydraulic energy. To this end a hydraulic station is generally provided in a casing situated above the jaws. The limitation of the space available, due both to the working conditions (the hole or trench to be excavated are generally of limited dimensions, and the whole of the hydraulic station must penetrate into them gradually together with the jaws) and to other constructional requirements, in practice reduces the working power to a maximum of about 25-30 HP, which is only a fraction of the power available in rotary drillers. Moreover the use of a hydraulic station with the consequent presence of hydraulic and electrical'connections is a source of continuous operational disturbances which reach a point of reducing the time in which such an implement can operate in practice by up to more than 25percent.

In the further development of the invention it has been found that as the environment in which said excavators have to work is generally rich with bentonitic mud, it is wise to make the zone in which the screw meshes with its corresponding nut screw work in a permanent bath of oil.

Moreover the ascending or descending working stroke of the nut screw on thescrew can take place only when said nut screw is made nonrotating, which is done by the nut screw engaging against opposing means. Advantageously these opposing means are constituted by the earth into which the jaws of the grab bite, these jaws being rigid withthe nut screw itself in the sense of rotation about the vertical axis (of drilling).

SUMMARY OF THE INVENTION It has now been found that certain problems arise both as regards the permanent operation in the bath of oil of the nut screw with respect to the screw, and with regard to the engagement between the nut screw and the walls of the excavation, especially when working in excavations bounded by parallel walls (trenches),

More particularly, the. axial movement of the nut screw in a sealed chamber containing the oil bath produces a piston or pumping effect, a problem which has to be solved.

Moreover in an excavation with parallel walls of the trench type, the implement is stabilized in order to make the nut screw immobile in the rotary sense (so giving it its axial movement), by making the nut screw, or rather the external casing with which the nut screw is rigid, engage against the parallel walls of the excavation. It has now been found that problems arise in making the beginning or end of rotation of the casing and the beginning or end of rotation of the nut screw strictly simultaneous.

These problems are resolved by the excavation apparatus according to the invention, which comprises jaws joined articulated to a nut screw and to a member idle on the extremity of the screw, and which is characterized in that the nut screw is prolonged in the form of a sleeve which extends beyond the end of the thread of the screw and there embraces in a sealed manner the unthreaded shank of the screw, while with said sleeve is engaged a counter sleeve in a telescopic manner, the lubricant being provided in the interspace between, at one end, the sleeve and counter sleeve, and, at the other end, the sleeve and screw, the means of articulation of the jaws of the grab being joined articulated to the sleeve and counter sleeve.

Advantageously said interspace is connected to an external reservoir with at least one expandable wall, capable of constituting a pressure equalizing lung for receiving the lubricant expelled from the interspace by said piston effect, and for returning said lubricant into the interspace when it is in a state: of suction.

According to a particular aspect of the invention, both the sleeve and counter sleeve are arranged in a protective casing which in-the case of the implement destined for the excavation of trenches or baffles has at least two parallel sides, the casing and the sleeve and counter sleeve comprisingmeans of reciprocal engagement in the rotary sense, said means having a certain degree of play between them so that arotation of a few degrees of the nut screw is possible: before dragging the easing into rotation.

BRIEF DESCRIPTION OF THE DRAWINGS Further characteristics and advantages of the invention will be more evident from the description of a preferred embodiment illustrated in the accompanying drawing by way of example in which: I I

FIG. 1 is a vertical diagrammatical section through a grab according to the invention, in which one blade is shown in the open position whereas the other is drawn DESCRIPTION OF PREFERRED EMBODIMENTS With reference to said figures, the implement can be coupled to the driving equipment M (FIGS. and 6) of a rotary drill, and for this purpose possesses a rod 1 provided at its end with a coupling section 2 comprising a hole 3 for receiving a coupling pin at the lower end of a rotary drill rod R (FIGS. 5 and 6). This coupling is made by means of a universal joint. The rod is driven by a rotary plate or table T (FIGS. 5 and 6) which consequently acts with all its considerable weight on the rod 1. A sleeve 4 is mounted on said rod 1 and at its top comprises a sealing and spacing cylinder 5 provided with a gland 6, so that between the sleeve 4 and rod 1 there remains an annular cylindrical interspace 7, for filling with a lubricant, preferably oil. At its lower end the sleeve comprises internally a hollow cylindrical body, internally threaded, which constitutes the nut screw and is indicated by the reference number 8, and which is rigidly fixed to the sleeve 4.

The rod 1 comprises a thread 11:, starting from a position slightly above that occupied in FIG. I by the sleeve 4, so that the lower end of the rod 1 constitutes the screw which engages with the nut screw.

The thread extends downwards, leaving however a section lbof the rod 1 at its lower extremity free of thread for the purposes hereinafter explained. More particularly a counter sleeve 11 is mounted externally on the lower end of the sleeve 8 with a sealing cylinder 9 and gland 10 between them, said counter sleeve being thus able to slide telescopically on the sleeve 4. Between the threaded part la of the rod 1 and the counter sleeve 11 an interspace 7a is hence formed in hydraulic communication with the interspace 7 by way of the "ion of engagement of the thread In with the internal thread of the nut screw 8.

On said lower section lb of the rod 1 a bearing 12 is mounted which externally supports a cylindrical body 13 welded rigidly to the lower end of the counter sleeve 11, said counter sleeve 11 being thus rotably supported idly both on the lower end of the rod 1 and on the lower end of the sleeve 4.

More particularly, on a prolongation 1c, of diameter less than the section 1b of the rod 1, and which is externally threaded, is mounted a cover 14 provided with holes 15, and end plates 16, 17 centrally provided with a screw 18 functioning as a plug are welded to the cylindrical body 13. Pivot rings 19, 20, in which the pivots 21, 22 ofthe blades 23, 24'engage, are rigidly welded to the plate 17. Pivot rings 27 and 28 are articulated on said blades 23 and 24 by way of pivot pins and 26, and are welded to the lower ends of tie rods 29, 30 respectively, which at their upper ends comprise eyelets 31, 32, which house pivot pins 33 for their articulated coupling to a tie flange 34 held rigid by means of two rings 35, 36, welded to the sleeve 4. The bolts 37 and 38 connect together the two half flanges which constitute the flange 34.

For lubricating the assembly l2, l3, 14, 16, which rotates like an enbloc idle at the lower end lb of the rod 1, a channel 130 external to the cylindrical body 13, together with channels 7b and 7c are provided for the passage of oil from the interspace 7a to the bearing 12 and the other members idly rotating at the end lb of the rod.

It is evident that when the nut screw 8 effects an axial movement from a point close to the end lb of the rod 1 towards a position corresponding to that shown in FIG. 1, a piston movement will take place in the interspaces 7, 7a, which because the liquid is uncompressible gives rise to problems if a permanent oil bath is to be maintained, in the sense that the interspaces 7 and 7a are to be maintained permanently full of lubricating oil.

For resolving the problem arising from this pumping effect, a channel 39 is provided according to the invention connected to the interspace 7a, which extends until it reaches a reservoir 40 which comprises at least one expandable wall, for example a wall of resilient material or a wall which may be retracted in the manner of a cylinder piston. In the example shown in detail in FIG. 4, a reservoir is illustrated comprising at least one wall of resiliently expandable material. More particularly the pressure equalizing reservoir comprises two heads 41, 42, which form upper and lower caps whose internal opposing sides comprise tapered zones 43, 44, connected by a tube 45, whose walls are provided with perforations 46. Externally the two heads 41 and 42 are connected together by a cylindrical tube 47 provided with perforations 48. Between the cylindrical tube 47 and the heads 42 there is a cylindrical tube 4Q of resiliently yieldable material, for example synthetic rubber.

The parts 41 and 42 areinternally hollow and are of sheet metal, and the tube 47 is alsoof sheet metal. Upperly there is an aperture 50 for oil make-up in the case of any oil loss. Fixing lugs 51 are provided upperly and fixing plates 52 lowerly.

The pressure equalizing reservoir so described is placed inside a casing which also contains the sleeve, counter sleeve, nut screw and screw assembly, the casing being of circular cross section in the case of circular excavations, whereas in the case of trench or baffle excavations it comprises at least two opposing parallel sides and end pieces connecting the parallel sides together.

Obviously in the case of trench or baffle excavations, at the end of the axial stroke of the nut screw 8 during which the blades or jaws 23, 24 close, the rod 1, which continues to rotate, could subject the sleeve, counter sleeve, nut screw and screw assembly plus the jaws themselves and their articulation means to excessive power, because of the high power availability.

In order to overcome the problem which could arise if the rotation of the rod 1 doesnot cease in time, a mechanism is provided which can slip if the resistance to rotation exceeds a certain limit. Such a mechanism could for example comprise a torque limiter L (FIG. 5) or a hydraulic motor assembly H (FIG. 6) known to be capable of considerable flexibility in the transmission of the rotation torque.

Again with regard to casings of non-circular shape, as soon as the casing is inserted into the corresponding trench or hole, the rotation of the rod which up to that moment was transmitted to the whole of the implement including the casing becomes opposed by the engagement betweenthe walls of the casing and the walls of the trench or baffle (contrary to that which takes place in the case of excavations of circular holes, in which the rotation of the rod is opposed by the engagement between the blades and the earth to be excavated). An axial movement of the nut screw can be produced only if its rotation is arrested.

It has been found that too sudden forces can be transmitted if there is no degree of play between the casing and the sleeve-counter sleeve assembly (with which the nut screw is rigid).

FIGS. 2 and 3 show cross sections of solutions to this problem. More particularly the halves of the tie flange 34 comprise projections 53 which rest between the substantially vertical ribs 54 fixed to the substantially parallel walls of the casing.

Further a polygonal, preferably square frame 55, is rigid with the counter sleeve 11 and a frame 56 of form substantially analogous to that of the frame 55 but slightly above it and capable of containing and circumscribing the frame 55 is rigid with the casing.

It is evident that when the sleeve 4 and counter sleeve 11 are made to rotate, they first rotate by a few degrees, in practice 34, before rotary engagement takes place between the projections 53 and the ribs 54 and frame 55 respectively.

In practice the nut screw 8 is made of a less resistant material than the steel screw la, for example a special bronze alloy.

It will be realized that any wear of the nut screw and any swarf deriving from it could produce jamming betweei'ithe nut screw and screw, if lubrication by means of a permanent oil bath is not carried out.

In practice operations is as follows. In the case ofa grab bucket for excavating circular holes, after the blades or jaws have closed and have been raised by a sufficient amount from the earth so that the blades no longer touch the earth, the rod 1 transmits a rotary movement in the desired direction to the whole of the implement including the blades, because there is no opposition to it. The bucket is then raised from the excavation made. In order to open the blades it is necessary once again to produce opposition to the rotation of the nut screw with respect to the screw. This is provided by the blades or jaws engaging with the heap of excavated material on to which the material just excavated is to be unloaded. The operator lowers the bucket until the blades touch the earth underneath and are braked. This immobilizing effect set up on the blades is transmitted to the counter sleeve 11 and through the tie rods 29 and 30 to the sleeve 4, because of whichthe nut screw can no longer rotate and is compelled to move axially and so open the blades and unload the bucket.

Contrary to that which might be supposed, it has been found particularly useful to use a very large or steep thread pitch on the screw, even though a large or steep pitch reduces the size of the forces which can be transmitted per unit of axial length of the screw. One of the advantages of a steep pitch is that when the blades or jaws are still they rapidly follow the axial movement of the nut screw in relation to the large pitch thread la, so that the blades are rapidly opened once the axial movement has started.

In practice, the constructional details may be substituted by equivalent technical means, and modifications may be made which fall within the scope of the invention.

Thus for example, the rod for very large depths may be formed from a number of components which slide one on the other in a telescopic manner.

I claim:

1. An apparatus for excavating holes and trenches, including a multi-jaw grab bucket with a driving rod having a screw-threaded section and in which the jaws are articulated at one point thereof through connecting arms to a nut screw screwed on said screw-threaded section and at another point thereof to an articulation member idle on the extremity of said driving rod, wherein according to the improvement, said nut screw has a sleevelike portion extending at least over a portion of said driving rod beyond said screw-threaded section thereof and defining therebetween a first interspace for a lubricant, a counter sleeve member telescopically engaging said sleeve-like portion and surrounding at least said screw-threaded section of said driving rod and defining therebetween a further inter space for a lubricant, said counter sleeve member being connected with said articulation member and sealing means for said interspaces.

2. An apparatus as claimed in claim 1, wherein said counter sleeve member is slideably mounted on said sleeve portion over an intermediate gland, and lowerly comprises annular members rotably mounted idly on the lower unthreaded end of said driving rod, bearings being provided between said annular members and said end.

3. An apparatus as claimed in claim 1, which comprises at least one passage between said further interspace for the lubricant, and the interstices existing between said annular members, said bearings and said end of the rod.

4. An apparatus as claimed in claim 1, wherein said screw-threaded section of said rod comprises a steep thread pitch.

5. An apparatus as claimed in claim 1, wherein both said sleeve portion and counter sleeve member are arranged in a protective casing, which in the case of the implement for excavating trenches or baffles has at least two parallel sides, the casing and the sleeve portion and counter sleeve member comprising means of reciprocal engagement in the rotational sense, said means having a certain degree of play between them, by which a rotation of a few degrees of the nut screw is possible before the casing is dragged into rotation.

6. An apparatus as claimed in claim 1, wherein when constructed with an external polygonal casing, the apparatus comprises a mechanism adapted for slip such as for example a torque limiter or ahydraulic mechanism interposed between the source of motive power and the rod of the implement.

7. An apparatus as claimed in claim 1, wherein at least one of said interspaces is connected to an external reservoir with at least one expandable wall, capable of constituting a pressure equalizing lung for receiving the lubricant expelled from said interspace by a piston effect, and for returning said lubricant to said interspace when suction conditions are set up in it.

8. An apparatus as claimed in claim 7, wherein said reservoir with at least one expandable wall includes an internal tubular body, with rigid perforated walls, in communication with said interspace, and comprising an enlarged lower head and an enlarged upper head, and an external tubular member of elastically deformable material such as e.g. synthetic rubber, the whole assembly being enclosed by an external rigid perforated shell.

* t t i 

1. An apparatus for excavating holes and trenches, including a multi-jaw grab bucket with a driving rod having a screw-threaded section and in which the jaws are articulated at one point thereof through connecting arms to a nut screw screwed on said screw-threaded section and at another point thereof to an articulation member idle on the extremity of said driving rod, wherein, according to the improvement, said nut screw has a sleevelike portion extending at least over a portion of said driving rod beyond said screw-threaded section thereof and defining therebetween a first interspace for a lubricant, a counter sleeve member telescopically engaging said sleeve-like portion and surrounding at least said screw-threaded section of said driving rod and defining therebetween a further interspace for a lubricant, said counter sleeve member being connected with said articulation member and sealing means for said interspaces.
 2. An apparatus as claimed in claim 1, wherein said counter sleeve member is slideably mounted on said sleeve portion over an intermediate gland, and lowerly comprises annular members rotably mounted idly on the lower unthreaded end of said driving rod, bearings being provided between said annular members and said end.
 3. An apparatus as claimed in claim 1, which comprises at least one passage between said further interspace for the lubricant, and the interstices existing between said annular members, said bearings and said end of the rod.
 4. An apparatus as claimed in claim 1, wherein said screw-threaded section of said rod comprises a steep thread pitch.
 5. An apparatus as claimed in claim 1, wherein both said sleeve portion and counter sleeve member are arranged in a protective casing, which in the case of the implement for excavating trenches or baffles has at least two parallel sides, the casing and the sleeve portion and counter sleeve member comprising means of reciprocal engagement in the rotational sense, said means having a certain degree of play between them, by which a rotation of A few degrees of the nut screw is possible before the casing is dragged into rotation.
 6. An apparatus as claimed in claim 1, wherein when constructed with an external polygonal casing, the apparatus comprises a mechanism adapted for slip such as for example a torque limiter or a hydraulic mechanism interposed between the source of motive power and the rod of the implement.
 7. An apparatus as claimed in claim 1, wherein at least one of said interspaces is connected to an external reservoir with at least one expandable wall, capable of constituting a pressure equalizing lung for receiving the lubricant expelled from said interspace by a piston effect, and for returning said lubricant to said interspace when suction conditions are set up in it.
 8. An apparatus as claimed in claim 7, wherein said reservoir with at least one expandable wall includes an internal tubular body, with rigid perforated walls, in communication with said interspace, and comprising an enlarged lower head and an enlarged upper head, and an external tubular member of elastically deformable material such as e.g. synthetic rubber, the whole assembly being enclosed by an external rigid perforated shell. 